Heat exchanger process

ABSTRACT

Heat exchanger processes are disclosed. A heat exchanger process uses a heat exchanger. The heat exchanger has a surface positioned to be contacted by a fluid. The heat exchanger process includes contacting the surface with the fluid by transporting the fluid through the heat exchanger and transferring heat between the surface and the fluid. The transporting is at a rate of less than 2 meters per second, the surface includes a fouling-resistant coating, the fluid includes particles known to cause fouling, or a combination thereof.

PRIORITY

This application claims priority to and benefit of U.S. Provisional Patent Application No. 63/058,744, entitled HEAT EXCHANGER PROCESS, filed Jul. 30, 2020, and PCT Application No. PCT/US2021/037637, filed Jun. 16, 2021, and entitled “HEAT EXCHANGER PROCESS” both of which are hereby incorporated by reference in their entirety.

FIELD OF THE INVENTION

The present invention is directed to heat exchanger processes. More particularly, the present invention is directed to such processes previously susceptible to fouling.

BACKGROUND OF THE INVENTION

Fouling is a known problem for heat transfer processes using heat exchangers. Fouling is known to create economic and operational problems driven by losses in efficiency. Losses in efficiency are based upon deterioration as well as loss of operational time associated with heat exchangers in operation.

Deposition and accumulation of unwanted materials, such as, scale, algae, suspended solids, and insoluble salts, occurs on internal or external surfaces of heat exchangers. Such deposition and accumulation creates mechanical and material stresses on heat exchangers that require maintenance, constrict flow-paths of heat transfer media, and can result in failure of the heat exchanger.

To combat such fouling, U.S. Pat. No. 6,782,943, entitled “Fouling Reduction Device for Tubular Heat Exchanger,” which is hereby incorporated by reference in its entirety, discloses devices used to reduce fouling. Such devices produce turbulence, which is not always practical for certain heat exchanger applications. Likewise, such devices create mechanical limitations and size limitations. Other mechanical implementations are known but suffer from similar drawbacks.

Other techniques that implement fouling control include limiting fluids that contact heat exchanger elements and/or avoiding process parameters that induce fouling. Such techniques involve pre-filtration and cooling water debris filters, foreign-object exclusion, acoustic monitoring, fluid treatment, microfiltration, membrane technology (reverse-osmosis or electrodeionization), ion-exchange resins, alkalinization (for example, ammonia, morpholine, ethanolamine, or sodium phosphate), control of oxygen dissolved in water (for example, by addition of hydrazine), addition of corrosion inhibitors, use of biocides (for example, inorganic chlorine and bromide compounds, chlorine and bromide cleavers, ozone and oxygen cleavers, or unoxidizable biocides), use of chemical fouling inhibitors (for example, chelating agents (like ethylenediaminetetraacetic acid), long-chain aliphatic amines, polyamines (like octadecylamin, helamin, or other film-forming amines), organic phosphonic acids (like etidronic acid), polyelectrolytes (like polyacrylic acid, polymethacrylic acid, and/or fluids with molecular weights lower than 10,000), additives to lower the melting point of process chemicals (like aluminum or magnesium), and/or magnetic water treatment. Each of these fouling control techniques causes expense and/or operational limitations.

A heat exchanger processes capable of resisting fouling that does not rely upon such fouling control techniques would be desirable in the art.

BRIEF DESCRIPTION OF THE INVENTION

In an embodiment, a heat exchanger process use a heat exchanger. The heat exchanger has a surface positioned to be contacted by a fluid. The heat exchanger process includes contacting the surface with the fluid by transporting the fluid through the heat exchanger and transferring heat between the surface and the fluid. The transporting is at a rate of less than 2 meters per second. The surface includes a fouling-resistant coating.

In another embodiment, a heat exchanger process uses a heat exchanger. The heat exchanger has a surface positioned to be contacted by a fluid. The heat exchanger process includes contacting the surface with the fluid by transporting the fluid through the heat exchanger and transferring heat between the surface and the fluid. The surface includes a fouling-resistant coating. The fluid includes particles are known to cause fouling.

Other features and advantages of the present invention will be apparent from the following more detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of a heat exchanger process, with a schematic heat exchanger with a heat transfer tube depicted transparent for illustration, according to an embodiment of the disclosure.

Wherever possible, the same reference numbers will be used throughout the drawings to represent the same parts.

DETAILED DESCRIPTION OF THE INVENTION

Provided is a heat exchanger processes capable of resisting fouling that does not rely upon known fouling control techniques. Embodiments of the heat exchanger process include, but are not limited to, being operational under what have previously been considered fouling conditions (for example, at flow rates that would otherwise cause fouling, such as, in portions of the system or in the entire system), having more flexible flow (for example, operating with laminar flow, operating with turbulent flow, operating with concurrent laminar and turbulent flow, or operating with sequential laminar and turbulent flow), having few or no cleaning cycles (for example, being devoid of pickling, water lancing, recirculating/blasting) with metals, abrasives, sponges, balls or mechanical cleaners like “bullet-type” tube cleaners)), operating without or with reduced pressure pulses or backflow cycles (or blowdown), operating at temperatures incompatible with polymers like polytetrafluoroethylene, being devoid of ions (for example, from ion implantation) or serving as a barrier to ions, having roughness (or smoothness) that would otherwise result in fouling, or a combination thereof.

Referring to FIG. 1 , in one embodiment, a heat exchanger process 100 uses a heat exchanger 101. The heat exchanger 101 has a surface 103 positioned to be contacted by a fluid 105. The heat exchanger process 100 includes contacting (step 102) the surface 103 with the fluid 105 by transporting the fluid 105 through the heat exchanger 101, and transferring (step 104) heat 107 between the surface 103 and the fluid 105. The surface 103 includes a fouling-resistant coating 109. The fouling-resistant coating 109 is directly or indirectly on the substrate 111. As used herein, the term “fouling-resistant” refers to having properties that reduce or eliminate fouling that would be present in identical operational configurations but for the presence of the properties.

The fouling-resistant coating 109 imparts the properties to the surface 103 that reduce or eliminate the fouling. Embodiments of the fouling-resistant coating 109 have a composition including carbon, hydrogen, silicon, oxygen, nitrogen, fluorine, and combinations thereof.

In one embodiment, the fouling-resistant coating 109 includes or consists of amorphous silicon and hydrogen (with incidental impurities, for example, from the substrate 111 and/or oxygen).

In one embodiment, the fouling-resistant coating 109 includes or consists of amorphous silicon and hydrogen (with incidental impurities, for example, from the substrate 111 and/or oxygen), with carbon (for example, from a functionalization distal from the substrate 111 or increasing in concentration distal from the substrate 111).

In one embodiment, the fouling-resistant coating 109 includes or consists of amorphous silicon, oxygen, and hydrogen (with incidental impurities, for example, from the substrate 111).

In one embodiment, the fouling-resistant coating 109 includes or consists of amorphous silicon, oxygen, and hydrogen (with incidental impurities, for example, from the substrate 111), with amorphous carbon (for example, increasing in concentration in regions distal from the substrate 111, increasing in concentration in regions distal from the oxygen, and/or increasing in concentration in regions proximal to the surface 103).

In one embodiment, the fouling-resistant coating 109 includes or consists of amorphous silicon, nitrogen, oxygen, and hydrogen (with incidental impurities, for example, from the substrate 111), with amorphous carbon (for example, increasing in concentration in regions distal from the substrate 111, increasing in concentration in regions distal from the oxygen, and/or increasing in concentration in regions proximal to the surface 103).

In one embodiment, the fouling-resistant coating 109 includes or consists of amorphous silicon, fluorine, and hydrogen (with incidental impurities, for example, from the substrate 111), with amorphous carbon (for example, increasing in concentration in regions distal from the substrate 111, increasing in concentration in regions distal from the oxygen, and/or increasing in concentration in regions proximal to the surface 103).

Further embodiments include molecular fragments deposited through precursors being heated to temperatures above the decomposition temperature of the precursor. Exemplary temperatures for the decomposition temperature are greater than 200° C., greater than 300° C., greater than 350° C., greater than 370° C., greater than 380° C., greater than 390° C., between 300° C. and 450° C., between 350° C. and 450° C., between 380° C. and 450° C., between 300° C. and 500° C., or any suitable combination, sub-combination, range, or sub-range therein.

Deposition techniques for the fouling-resistant coating 109 include expanding the chemical vapor deposition processes disclosed in U.S. Pat. No. 6,444,326, entitled “SURFACE MODIFICATION OF SOLID SUPPORTS THROUGH THE THERMAL DECOMPOSITION AND FUNCTIONALIZATION OF SILANES,” U.S. Pat. No. 9,777,368, entitled “CHEMICAL VAPOR DEPOSITION COATING, ARTICLE, AND METHOD,” U.S. Pat. No. 9,975,143, entitled “CHEMICAL VAPOR DEPOSITION FUNCTIONALIZATION,” U.S. Pat. No. 9,915,001, entitled “CHEMICAL VAPOR DEPOSITION PROCESS AND COATED ARTICLE,” U.S. Pat. No. 10,087,521, entitled “SILICON-NITRIDE-CONTAINING THERMAL CHEMICAL VAPOR DEPOSITION COATING,” U.S. Pat. No. 10,323,321, entitled “THERMAL CHEMICAL VAPOR DEPOSITION PROCESS AND COATED ARTICLE,” U.S. Pat. No. 10,487,403, entitled “FLUORO-CONTAINING THERMAL CHEMICAL VAPOR DEPOSITION PROCESS AND ARTICLE,” and U.S. Pat. No. 10,604,660, entitled “WEAR RESISTANT COATING, ARTICLE, AND METHOD,” each of which are incorporated by reference in their entirety. The expanding of the process includes combining the deposition techniques within such references to previously-considered unworkable dimensions, such as, having a maximum rigid length of greater than 2.1 meters. Such expansion is enabled by modification of flow within a chamber/vessel, modification of flow in and out of a chamber/vessel, modification of heating elements for heating a vessel, and/or modifying vessel configurations to allow larger lengths (for example, lengths of greater than 2.5 meters, greater than 3 meters, greater than 5 meters, greater than 6 meters, between 2.5 meters and 7 meters, between 3 meters and 7 meters, between 5 meters and 7 meters, between 5 meters and 6 meters, between 6 meters and 7 meters, or any suitable combination, sub-combination, range, or sub-range therein).

Suitable such precursors include, but are not limited to, silane, silane and ethylene, silane and an oxidizer, dimethylsilane, dimethylsilane and an oxidizer, trimethylsilane, trimethylsilane and an oxidizer, dialkylsilyl dihydride, alkylsilyl trihydride, non-pyrophoric species (for example, dialkylsilyl dihydride and/or alkylsilyl trihydride), thermally-reacted material (for example, carbosilane and/or carboxysilane, such as, amorphous carbosilane and/or amorphous carboxysilane), species capable of a recombination of carbosilyl (disilyl or trisilyl fragments), methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylmethoxysilane, trimethylethoxysilane, ammonia, hydrazine, trisilylamine, Bis(tertiary-butylamino)silane, 1,2-bis(dimethylamino)tetramethyldisilane, dichlorosilane, hexachlorodisilane), organofluorotrialkoxysilane, organofluorosilylhydride, organofluoro silyl, fluorinated alkoxysilane, fluoroalkylsilane, fluorosilane, tridecafluoro 1,1,2,2-tetrahydrooctylsilane, (tridecafluoro-1,1,2,2-tetrahydrooctyl) triethoxysilane, triethoxy (3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluoro-1-octyl) silane, (perfluorohexylethyl) triethoxysilane, silane (3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl) trimethoxy-, or a combination thereof.

Fouling is identifiable, for example, over time by an increase in thermal resistance, a constricting of flow, an increase in velocity of the flow (for example, due to the constricting), degradation of mechanical properties, increased corrosion, increased surface roughness and/or frictional resistance, decreased effluent temperature, an increased pressure drop, increased carbon dioxide emissions, decreased operational efficiency (for example, based upon a reduction in heat transfer), or through other means described herein. Fouling is further identifiable based upon detailed explanations in known processes, for example, in Mostafa M. Awad (2011), “Fouling of Heat Transfer Surfaces, Heat Transfer—Theoretical Analysis, Experimental Investigations and Industrial Systems,” Prof. Aziz Belmiloudi (Ed.), ISBN: 978-953-307-226-5, InTech, available from: http://www.intechopen.com/books/heat-transfer-theoretical-analysis-experimentalinvestigations-and-industrial-systems/fouling-of-heat-transfer-surfaces, and in Hassan Al-Haj Ibrahim (2012), “Fouling in Heat Exchangers,” InTech, available from: https://cdn.intechopen.com/pdfs/39353/InTech-Fouling_in_heat_exchangers.pdf, the entirety of which are both incorporated by reference.

In one embodiment, while the heat exchanger process 100 operates under conditions that would cause the fouling in the absence of the fouling-resistant coating 109, the flow rate within the heat exchanger 101 is at a rate of less than 2 meters per second, less than 1 meter per second, less than 0.1 meters per second, between 1 and 2 meters per second, between 0.1 and 1 meters per second, between 0.1 and 0.5 meters per second, between 0 and 0.1 meters per second, between 0.01 and 0.1 meters per second, temporarily stagnant, or an suitable combination, sub-combination, range, or sub-range therein.

In one embodiment, the fouling-resistant coating 109 has surface energy that allows operation under conditions that would otherwise cause the fouling in the absence of the fouling-resistant coating 109. For example, in one embodiment, the surface energy is hydrophobic, such as, having a water contact angle of within the range of between 115° and 170°, such as, between 115° and 140°, between 118° and 135°, between 120° and 121° (for example, on 304 stainless steel), between 125° and 126° (for example, on 316 stainless steel), or any suitable combination, sub-combination, range, or sub-range therein. Additionally or alternatively, in one embodiment, the surface energy is oleophobic, such as, having a hexadecane contact angle within the range of between 65° and 110°, such as, between 65° and 90°, between 70° and 85°, between 77° and 78° (for example, on 304 stainless steel), between 75° and 76° (for example, on 316 stainless steel), or any suitable combination, sub-combination, range, or sub-range therein.

In one embodiment, while the heat exchanger process 100 operates under conditions that would cause the fouling in the absence of the fouling-resistant coating 109, the fluid 105 includes foulants. Suitable foulants include, but are not limited to, materials having unsaturated and unstable compounds, inorganic salts and trace elements (such as, sulfur, nitrogen, and/or oxygen), organic acids, inorganic acids, corrosive acids (such as, hydrochloric acid, sulfuric acid, nitric acids, chromic acid, acetic acid, and/or hydrofluoric acid), corrosive bases (ammonium hydroxide, potassium hydroxide (caustic potash), and/or sodium hydroxide (caustic soda)), microbes, seawater/brine, carbonaceous materials, catalytic products, minerals (for example, such as, calcium, calcium carbonate, calcium sulfate, phosphorus, scaling minerals), chelating molecules (for example, tetracycline, N-hydroxypyridine-2-on, adenosine triphosphate, deoxynucleotide monophosphate, or combinations thereof), proteins (for example, from aquatic organisms, fatty acids, organic oil, etc.), biological fluids (for example, blood, plasma, platelets, red blood cells, white blood cells, stem cells, globulins, chondrocytes, cultures, vaccines, coagulation factors, toxoids, complexes, allergenics, pollens, venoms, or combinations thereof), or combinations thereof.

In one embodiment, the heat exchanger process 100 includes using the heat exchanger 101 in a process supporting a system for petrochemical processing, refining, nuclear cooling systems, oil-fired system cooling, gas-fired system cooling, boilers, pharmaceutical manufacturing, biological processing, food service production, or combinations thereof.

In one embodiment, while the heat exchanger process 100 operates under conditions that would cause the fouling in the absence of the fouling-resistant coating 109, heat transfer between the substrate 111 and the fluid 105 is greater than heat transfer between a comparative coating of polyethylene terephthalate. The greater heat transfer is based upon the fouling-resistant coating 109 having a thickness that is lower than the comparative coating and/or at a thickness of between 50 nanometers and 10,000 nanometers, between 50 nanometers and 1,000 nanometers, between 100 nanometers and 800 nanometers, between 200 nanometers and 600 nanometers, between 200 nanometers and 10,000 nanometers, between 500 nanometers and 3,000 nanometers, between 500 nanometers and 2,000 nanometers, between 500 nanometers and 1,000 nanometers, between 1,000 nanometers and 2,000 nanometers, between 1,000 nanometers and 1,500 nanometers, between 1,500 nanometers and 2,000 nanometers, 800 nanometers, 1,200 nanometers, 1,600 nanometers, 1,900 nanometers, or any suitable combination, sub-combination, range, or sub-range therein. More particularly, in one embodiment, the thickness of the coating 121 is between 50 nm and 900 nm, between 100 m and 800 nm, between 200 nm and 400 nm, between 300 nm and 600 nm, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 850 nm, 900 nm, or any suitable combination, sub-combination, range, or sub-range therein.

In one embodiment, while the heat exchanger process 100 operates under conditions that would cause the fouling in the absence of the fouling-resistant coating 109, based upon information identified as parameters for appropriate use of stainless steel within the Committee of Stainless Steel Producers, “The Role Stainless Steel in Industrial Heat Exchangers,” Stainless Steel Industry Data, archived Sep. 4, 2012, available from: https://www.nickelinstitute.org/˜/media/Files/TechnicalLiterature/RoleofStainlessSteelsinIndustrialHeatExchangers_9005_.ashx, the entirety of which is incorporated by reference.

In one embodiment, while the heat exchanger process 100 operates under conditions that would cause the fouling in the absence of the fouling-resistant coating 109, the heat exchanger process 100 includes extending repair cycles, avoiding scheduled replacements, operating with less downtime, using streams that are known to create contaminants, or otherwise operating outside the scope of best practices established without the fouling-resistant coating 109.

Suitable embodiments include the substrate 111 including or being metal, metallic material, ceramic, glass, ceramic matrix composite, or a combination thereof. In a further embodiment, the metallic material is tempered or non-tempered, has grain structures that are equiaxed, directionally-solidified, and/or single crystal, has amorphous or crystalline structures, is a foil, fiber, a cladding, and/or a film. Suitable metallic materials include, but are not limited to, ferrous-based alloys, non-ferrous-based alloys, nickel-based alloys, stainless steels (martensitic or austenitic), aluminum-containing materials (for example, alloys, Alloy 6061, aluminum), composite metals, or combinations thereof. In an alternative embodiment, the metallic material is replaced with a non-metallic material.

In one embodiment, the metallic material has a first iron concentration and a first chromium concentration, the first iron concentration being greater than the first chromium concentration. For example, suitable values for the first iron concentration include, but are not limited to, by weight, greater than 50%, greater than 60%, greater than 66%, greater than 70%, between 66% and 74%, between 70% and 74%, or any suitable combination, sub-combination, range, or sub-range therein. Suitable values for the first chromium concentration include, but are not limited to, by weight, greater than 10.5%, greater than 14%, greater than 16%, greater than 18%, greater than 20%, between 14% and 17%, between 16% and 18%, between 18% and 20%, between 20% and 24%, or any suitable combination, sub-combination, range, or sub-range therein.

In one embodiment, the metallic material is or includes a composition, by weight, of up to 0.08% carbon, between 18% and 20% chromium, up to 2% manganese, between 8% and 10.5% nickel, up to 0.045% phosphorus, up to 0.03% sulfur, up to 1% silicon, and a balance of iron (for example, between 66% and 74% iron).

In one embodiment, the metallic material is or includes a composition, by weight, of up to 0.08% carbon, up to 2% manganese, up to 0.045% phosphorus, up to 0.03% sulfur, up to 0.75% silicon, between 16% and 18% chromium, between 10% and 14% nickel, between 2% and 3% molybdenum, up to 0.1% nitrogen, and a balance of iron.

In one embodiment, the metallic material is or includes a composition, by weight, of up to 0.03% carbon, up to 2% manganese, up to 0.045% phosphorus, up to 0.03% sulfur, up to 0.75% silicon, between 16% and 18% chromium, between 10% and 14% nickel, between 2% and 3% molybdenum, up to 0.1% nitrogen, and a balance of iron.

In one embodiment, the metallic material is or includes a composition, by weight, of between 14% and 17% chromium, between 6% and 10% iron, between 0.5% and 1.5% manganese, between 0.1% and 1% copper, between 0.1% and 1% silicon, between 0.01% and 0.2% carbon, between 0.001% and 0.2% sulfur, and a balance nickel (for example, 72%).

In one embodiment, the metallic material is or includes a composition, by weight, of between 20% and 24% chromium, between 1% and 5% iron, between 8% and 10% molybdenum, between 10% and 15% cobalt, between 0.1% and 1% manganese, between 0.1% and 1% copper, between 0.8% and 1.5% aluminum, between 0.1% and 1% titanium, between 0.1% and 1% silicon, between 0.01% and 0.2% carbon, between 0.001% and 0.2% sulfur, between 0.001% and 0.2% phosphorus, between 0.001% and 0.2% boron, and a balance nickel (for example, between 44.2% and 56%).

In one embodiment, the metallic material is or includes a composition, by weight, of between 20% and 23% chromium, between 4% and 6% iron, between 8% and 10% molybdenum, between 3% and 4.5% niobium, between 0.5% and 1.5% cobalt, between 0.1% and 1% manganese, between 0.1% and 1% aluminum, between 0.1% and 1% titanium, between 0.1% and 1% silicon, between 0.01% and 0.5% carbon, between 0.001% and 0.02% sulfur, between 0.001% and 0.02% phosphorus, and a balance nickel (for example, 58%).

In one embodiment, the metallic material is or includes a composition, by weight, of between 25% and 35% chromium, between 8% and 10% iron, between 0.2% and 0.5% manganese, between 0.005% and 0.02% copper, between 0.01% and 0.03% aluminum, between 0.3% and 0.4% silicon, between 0.005% and 0.03% carbon, between 0.001% and 0.005% sulfur, and a balance nickel (for example, 59.5%).

In one embodiment, the metallic material is or includes a composition, by weight, of between 17% and 21% chromium, between 2.8% and 3.3% iron, between 4.75% and 5.5% niobium, between 0.5% and 1.5% cobalt, between 0.1% and 0.5% manganese, between 0.2% and 0.8% copper, between 0.65% and 1.15% aluminum, between 0.2% and 0.4% titanium, between 0.3% and 0.4% silicon, between 0.01% and 1% carbon, between 0.001 and 0.02% sulfur, between 0.001 and 0.02% phosphorus, between 0.001 and 0.02% boron, and a balance nickel (for example, between 50% and 55%).

In one embodiment, the metallic material is or includes a composition, by weight, of between 2% and 3% cobalt, between 15% and 17% chromium, between 5% and 17% molybdenum, between 3% and 5% tungsten, between 4% and 6% iron, between 0.5% and 1% silicon, between 0.5% and 1.5% manganese, between 0.005 and 0.02% carbon, between 0.3% and 0.4% vanadium, and a balance nickel.

In one embodiment, the metallic material is or includes a composition, by weight, of up to 0.15% carbon, between 3.5% and 5.5% tungsten, between 4.5% and 7% iron, between 15.5% and 17.5% chromium, between 16% and 18% molybdenum, between 0.2% and 0.4% vanadium, up to 1% manganese, up to 1% sulfur, up to 1% silicon, up to 0.04% phosphorus, up to 0.03% sulfur, and a balance nickel.

In one embodiment, the metallic material is or includes a composition, by weight, of up to 2.5% cobalt, up to 22% chromium, up to 13% molybdenum, up to 3% tungsten, up to 3% iron, up to 0.08% silicon, up to 0.5% manganese, up to 0.01% carbon, up to 0.35% vanadium, and a balance nickel (for example, 56%).

In one embodiment, the metallic material is or includes a composition, by weight, of between 1% and 2% cobalt, between 20% and 22% chromium, between 8% and 10% molybdenum, between 0.1% and 1% tungsten, between 17% and 20% iron, between 0.1% and 1% silicon, between 0.1% and 1% manganese, between 0.05 and 0.2% carbon, and a balance nickel.

In one embodiment, the metallic material is or includes a composition, by weight, of between 0.01% and 0.05% boron, between 0.01% and 0.1% chromium, between 0.003% and 0.35% copper, between 0.005% and 0.03% gallium, between 0.006% and 0.8% iron, between 0.006% and 0.3% magnesium, between 0.02% and 1% silicon+iron, between 0.006% and 0.35% silicon, between 0.002% and 0.2% titanium, between 0.01% and 0.03% vanadium+titanium, between 0.005% and 0.05% vanadium, between 0.006% and 0.1% zinc, and a balance aluminum (for example, greater than 99%)

In one embodiment, the metallic material is or includes a composition, by weight, of between 0.05% and 0.4% chromium, between 0.03% and 0.9% copper, between 0.05% and 1% iron, between 0.05% and 1.5% magnesium, between 0.5% and 1.8% manganese, between 0.5% and 0.1% nickel, between 0.03% and 0.35% titanium, up to 0.5% vanadium, between 0.04% and 1.3% zinc, and a balance aluminum (for example, between 94.3% and 99.8%).

In one embodiment, the metallic material is or includes a composition, by weight, of between 0.0003% and 0.07% beryllium, between 0.02% and 2% bismuth, between 0.01% and 0.25% chromium, between 0.03% and 5% copper, between 0.09% and 5.4% iron, between 0.01% and 2% magnesium, between 0.03% and 1.5% manganese, between 0.15% and 2.2% nickel, between 0.6% and 21.5% silicon, between 0.005% and 0.2% titanium, between 0.05% and 10.7% zinc, and a balance aluminum (for example, between 70.7% to 98.7%).

In one embodiment, the metallic material is or includes a composition, by weight, of between 0.15% and 1.5% bismuth, between 0.003% and 0.06% boron, between 0.03% and 0.4% chromium, between 0.01% and 1.2% copper, between 0.12% and 0.5% chromium+manganese, between 0.04% and 1% iron, between 0.003% and 2% lead, between 0.2% and 3% magnesium, between 0.02% and 1.4% manganese, between 0.05% and 0.2% nickel, between 0.5% and 0.5% oxygen, between 0.2% and 1.8% silicon, up to 0.05% strontium, between 0.05% and 2% tin, between 0.01% and 0.25% titanium, between 0.05% and 0.3% vanadium, between 0.03% and 2.4% zinc, between 0.05% and 0.2% zirconium, between 0.150 and 0.2% zirconium+titanium, and a balance of aluminum (for example, between 91.7% and 99.6%).

In one embodiment, the metallic material is or includes a composition, by weight, of between 0.4% and 0.8% silicon, up to 0.7% iron, between 0.15% and 0.4% copper, up to 0.15% manganese, between 0.8% and 1.2% magnesium, between 0.04% and 0.35% chromium, up to 0.25% zinc, up to 0.15% titanium, optional incidental impurities (for example, at less than 0.05% each, totaling less than 0.15%), and a balance of aluminum (for example, between 95% and 98.6%).

In one embodiment, the metallic material is or includes a composition, by weight, of between 11% and 13% silicon, up to 0.6% impurities/residuals, and a balance of aluminum.

In one embodiment, the metallic material is or includes a composition, by weight, of between 0.7% and 1.1% magnesium, between 0.6% and 0.9% silicon, between 0.2% and 0.7% iron, between 0.1% and 0.4% copper, between 0.05% and 0.2% manganese, 0.02% and 0.1% zinc, 0.02% and 0.1% titanium, and a balance aluminum. In a further embodiment, the metallic material is Alloy 6061.

While the invention has been described with reference to one or more embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. In addition, all numerical values identified in the detailed description shall be interpreted as though the precise and approximate values are both expressly identified. 

What is claimed is:
 1. A heat exchanger process using a heat exchanger, the heat exchanger having a surface positioned to be contacted by a fluid, the heat exchanger process comprising: contacting the surface with the fluid by transporting the fluid through the heat exchanger; and transferring heat between the surface and the fluid; wherein the transporting is at a rate of less than 2 meters per second; wherein the surface includes a fouling-resistant coating.
 2. The heat exchanger process of claim 1, wherein transporting concurrently includes laminar and turbulent flow of the fluid.
 3. The heat exchanger process of claim 1, wherein transporting consist of laminar flow of the fluid.
 4. The heat exchanger process of claim 1, wherein transporting consist of turbulent flow of the fluid.
 5. The heat exchanger process of claim 1, wherein the fluid includes particles known to cause fouling.
 6. The heat exchanger process of claim 1, wherein the fluid includes corrosion products known to cause fouling.
 7. The heat exchanger process of claim 1, wherein the fluid includes crystals.
 8. The heat exchanger process of claim 1, wherein the fluid includes biological material.
 9. The heat exchanger process of claim 1, wherein the fluid includes non-homogenous materials.
 10. The heat exchanger process of claim 1, wherein the fluid includes impure materials.
 11. The heat exchanger process of claim 1, wherein the fluid flows at a first rate, then a second rate, the first rate differing from the second rate by at least 1 meter per second.
 12. The heat exchanger process of claim 1, wherein the surface has a roughness that induces fouling in the absence of the fouling-resistant coating.
 13. The heat exchanger process of claim 1, wherein the heat exchanger has a shell and one or more tubes and the surface is within the shell.
 14. The heat exchanger process of claim 13, wherein the shell includes segmented baffles arranged at a distance of less than one fifth of a diameter of the shell.
 15. The heat exchanger process of claim 1, wherein the heat exchanger is a low-finned tube heat exchanger.
 16. The heat exchanger process of claim 1, wherein the heat exchanger is a plate heat exchanger.
 17. The heat exchanger process of claim 1, wherein the fluid is a gas.
 18. The heat exchanger process of claim 1, wherein the fluid is a liquid.
 19. The heat exchanger process of claim 1, wherein the fouling-resistant coating includes amorphous silicon, hydrogen, and carbon.
 20. A heat exchanger process using a heat exchanger, the heat exchanger having a surface positioned to be contacted by a fluid, the heat exchanger process comprising: contacting the surface with the fluid by transporting the fluid through the heat exchanger; and transferring heat between the surface and the fluid; wherein the surface includes a fouling-resistant coating; wherein the fluid includes particles known to cause fouling. 